Automatic drain valve

ABSTRACT

An automatic drain valve for an air line filter and the like which discriminates between fluids of different viscosities, i.e., air and water, said valve being characterized in that the drain valve member thereof is seated when exposed to the lower viscosity fluid (air) and is unseated when exposed to the higher viscosity fluid (water) by reason of the difference in pressure drop across restrictor means through which the fluids flow. The valve herein is further characterized in that it has a downwardly extending inlet passage which opens near the bottom of the filter bowl and which is so arranged that when the water level in the filter bowl rises to the upper portion of the inlet passage to effect unseating of the drain valve member, the air pressure acting on the water in the filter bowl will cause drainage of the water from the filter bowl until the water level drops down to the lower open end of the inlet passage.

United States Patent Nilges 51 July 11,1972

[54] AUTOMATIC DRAIN VALVE [72] Inventor: William C. Nilges, Kalamazoo,Mich.

[731 Assignee: ParkerJlannlfin Corporation, Cleveland,

Ohio

[22] Filed: Sept. 25, I970 [2 l] Appl. No.2 75,570

Primary Examiner-Alan Cohan Attomey-0berlin, Maky, Donelly & Renner [57]ABSTRACT An automatic drain valve for an air line filter and the likewhich discriminates between fluids of different viscosities, i.e., airand water, said valve being characterized in that the drain valve memberthereof is seated when exposed to the lower viscosity fluid (air) and isunseated when exposed to the higher viscosity fluid (water) by reason ofthe difi'erence in pressure drop acrw restrictor means through which thefluids flow. The valve herein is further characterized in that it has adownwardly extending inlet passage which opens near the bottom of thefilter bowl and which is so arranged that when the water level in thefilter bowl rises to the upper portion of the inlet passage to eflectunseating of the drain valve member, the air presure acting on the waterin the filter bowl will cause drainage of the water from the filter bowluntil the water level drops down to the lower open end of the inletpassage.

9Clslms,2DrawingFlgures PATENTEnJuL 1 1 m2 INVENTOR.

w WILL/AM C. Ill/L665 ATTORNEYS AUTOMATIC mum VALVE BACKGROUND OF THEINVENTION Pneumatic power systems generally include between thecompressors and pneumatic actuators thereof air line filters whosefunction is to remove water and foreign particles which would corrodeand damage the downstream equipment such as valves and actuators. Suchair line filters comprise a body containing compressed air inlet andoutlet passages, a deflector for inducing whirling motion to thecompressed air to remove water therefrom by cyclonic or centrifugalaction, and a filter element through which the compressed air passes tofilter out foreign particles. The body usually has secured thereto afilter bowl which provides a quiet zone in which the water removed fromthe air by centrifugal action is collected and from which the water isperiodically drained either by opening a manually operated drain valveor by opening of an automatic drain valve.

When an automatic drain valve is provide in the filter bowl, the valvemember is generally of quite small size and is actuated by a floatdisposed for upward and downward movement in the filter bowl, and, ofcourse, the larger the drain passage and the greater the air pressure,the larger the float that is required to unseat the pressure seateddrain valve member. As evident, the buoyant force must overcome theseating force of air pressure times the area of the seat whereby if thepressure and seat diameter are doubled, the buoyant force must beincreased eight times. As an example of a float-type automatic drainvalve for an air line filter, reference may be had to the patent toLansky US. Pat. No. 3,330,292 dated July I l, I967 wherein a pressureseated valve member of relatively small size is unseated by a floatwhich is pivotally mounted in a closure plug in the bottom of the filterbowl and which is linked to the drain valve member to unseat it when thewater level in the filter bowl (at prescribed air pressure) reaches apredetermined level.

In view of the small size of the drain valve member in known automaticdrain valves, the operating forces are relatively small, and because thevalve member is seated by air pressure in the filter bowl, the waterlevel at which the float will open the drain valve member will vary bychange in air pressure thus to impose a limit of use of the air linefilter to a system having a prescribed range of air pressures, orrequiring different floats for different air pressure ranges. Moreover,the small size drain passage in the known float-type automatic drainvalves makes it desirable to provide a sump in the closure plug whereinparticles of foreign matter removed by centrifugal force may settle soas not to clog the small drain passage of the automatic drain valve, thesump being provided with a removable drain plug so that the collectedsediment may be periodically drained therefrom.

SUMMARY OF THE INVENTION Contrary to known automatic drain valves forair line filters and the like, the present automatic drain valve is ofsimple, low cost construction comprising a valve body secured in anopening in the bottom of the filter bowl and a drain valve membermovable in the body to open and close the drain opening thereofaccording to whether the drain valve member is exposed to air (the lowerviscosity fluid) or to water (the higher viscosity fluid).

The automatic drain valve has large size passages therein thus to entailapplication of large operating forces thereon to insure reliable andefficient operation even under conditions of dirty water which may passtherethrough from the filter bowl.

The automatic drain valve herein also is operative over a wide range offilter bowl pressure and is insensitive to vibration, the drain valvemember being seated with increasing force as the bowl pressure increasesthus to enable the use of a simple seat structure.

It is a further object of this invention to provide an automatic drainvalve which allows water to accumulate in the filter bowl to arelatively high and constant level before the drain valve member isactuated to open position, but once the drain valve member has moved toopen position, the filter bowl is substantially completely drained.

Another object of this invention is to provide an automatic drain valvein which the movable drain valve member is seated by the pressure of thelower viscosity fluid (air) in a chamber having restricted communicationwith the upstream and downstream sides of the valve member when thelevel of the higher viscosity fluid (water) is such that there is noflow thereof through the restricted communication between the upstreamside of the valve member and the chamber. The movable valve member isunseated by the pressure of the higher viscosity fluid (water) when suchfluid commences to flow through the restricted communication between theupstream side and the chamber whereby the pressure of the lowerviscosity fluid in the chamber is decreased through the restrictedcommunication of the chamber with the downstream side of the movablevalve member. The unseating of the movable valve member pennits rapiddraining of the filter bowl under the influence of air pressure actingon the water in the filter bowl.

As a further feature of the present invention, the automatic drain valveherein has a submerged inlet passage communicating with the water nearthe bottom of the filter bowl. Once the drain valve member has beenmoved to open position when exposed to the water reaching apredetermined level above the submerged opening of the said submergedpassage, the air pressure in the filter bowl lifts the water through thesubmerged passage to permit substantial emptying of the water until thewater level drops below the opening in the submerged passage.

Other objects and advantages of the present invention will appearhereinafter.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a central verticalcross-section view of an air line filter having the automatic drainvalve constituting the present invention installed in the bottom of thefilter bowl; and

FIG. 2 is an enlarged fragmentary cross-section view of the lowerportion of the filter bowl showing the automatic drain valve incross-section.

DETAILED DESCRIPTION OF THE INVENTION Referring first to FIG. I, the airline filter herein shown for illustrative purposes only, comprises abody 1 having an air inlet port 2, an air outlet port 3, and a centerpost 4 through which the filter element 5 is sealingly clamped by thespring retainer means 6 to the downwardly depending annular boss 7 insaid body I. The filter element 5 may be of conventional form such as aribbon type filter which provides edge filtration to move fine particlesor a porous sintered bronze filter.

The filter bowl 8 is clamped against a gasket 9 in said body 1 as bymeans of the clamp collar 10 which is secured to the body I as by screws(not shown).

The air that enters the body 1 through the inlet 2 has imparted theretoa whirling motion by the deflector plate ll whereby larger or heaviersolid particles and water particles in the air are thrown out bycentrifugal force so as to gravitate along the side wall of the bowl 8.The lower baffle plate 12 stops the whirling motion of the air to thusprovide a quiet zone ill in the lower portion of the filter bowl 8 sothat the solids and liquid remain trapped and quiescent in the lowerportion of the filter bowl 8. The whirling air moves around the filterelement 5 and finds its way to the outlet 3 through the myriad ofopenings in said filter element 5.

Secured in the bottom of the filter bowl 8 is an automatic drain valve14, the construction and operation of which will now be described indetail, particularly with reference to FIG. 2.

As shown in FIG. 2, the automatic drain valve 14 comprises a two-partbody 15-16 which forms inlet ports 17, a valve seat l8, and a drainpassage or outlet port 19, the lower body part 16 having a reduced sternportion 20 which is sealed as by the O-ring 21 to the opening throughthe bottom of the filter bowl 8 and which is secured to the bowl 8 as bymeans of the snap ring 23. The upper body part 15 forms a cylinder for apistonlike valve member 24 having its lower end movable into and out ofengagement with the seat 18. The drain valve member 24 is biased toseated position by means of the spring 25 and defines with the upperbody part 15 a primary restriction 26 and a secondary restriction 27preferably in the form of an annular clearance between the outsidediameter of the drain valve member 24 and the wall of the bore in theupper body part 15.

The downstream side of the primary restriction 26 is com municated withthe chamber 28 via the peripheral groove 29 and the openings 30 in thedrain valve member 24. The chamber 28 in turn has minusculecommunication with the drain passage 19 via the secondary restriction 27and the small cross hole 31 which opens at the periphery of the valvemember 24 and which intersects the central passage 32 leading to thedrain passage 19.

Secured to the upper body part 15 is a skirt member 34 having one ormore openings 35 at its upper end and defining a downwardly extendinginlet passage 36 which opens near the bottom of the filter bowl 8. Ashereinafter explained in detail, when the water level rises to the levelwhereat the valve member 24 is moved away from the seat 18, the flow ofwater from the filter bowl 8 will continue until the water level dropsbelow the lower edge of the skin member 34.

When the water level in the bow18 and in the skirt member 34 is belowthe upstream end of the primary restriction 26 and the upper edges ofthe inlet openings 17, the flow of air from the chamber 28 to the drainpassage 19 via the second restriction (clearance 27 and small opening31) is so slight that the pressure on opposite sides of the drain valvemember 24 are substantially equalized through the primary restriction26, whereby the drain valve member 24 is held in seated position by theforce exerted by the spring 25, by gravity, and the air pressure in thechamber 28 acting on the area A which is greater than the upward forceresulting from the pressure acting on the annular area 8. Thus, thevalve member 24 is held in seated position when the water level is belowthe upper edges of the inlet ports I! and the lower upstream end of theprimary restriction 26.

Now, when the water level rises above ports 17, air in the passage 36 isdisplaced through openings 35 until the water level reaches the lowerupstream end of the primary restriction 26 at which time the increasedpressure drop across restriction 26 will permit a decrease in airpressure in chamber 28 via the secondary restriction 27. As the airpressure in the chamber 28 decreases relative to the upward pressureacting on the annular area B, the point will be reached where the thenpredominant upward force on the area B will overcome the bias of thespring 25, the weight of the drain valve member 24, and the low airpressure acting downwardly on the area A of the drain valve member 24.When this occurs, the drain valve member 24 will be forced upwardly awayfrom the seat 18 to initiate drain flow from the filter bowl 8 throughthe passage 36, the inlet ports [7 and the drain passage 19.

When drain valve member 24 has thus been moved upwardly away from seat18, the pressure drop thereat and at the openings 35 relative to thepressure at the lower end of the inlet passage 36 will maintaincontinued upward water flow through passage 36 under the influence ofair pressure acting on the surface of the water around the skirt member34 until the water level drops below the lower edge of the skirt member34. When that occurs, water flows downwardly in passage 36 thus to allowair to flow into chamber 28 via the primary restriction 26 to build upin the chamber 28 to urge the valve member 24 downwardly against theseat 18 to prevent air leakage except the small amount which leaksthrough the secondary restriction 27.

I, therefore, particularly point out and distinctly claim as myinvention:

1. An automatic drain valve for an air line filter and the like having awater collecting bowl comprising a valve body having a passage throughwhich water in the bowl may be drained and having a valve seat; saidpassage, upstream of said seat, having a downwardly extending portionwhich has upper and lower openings leading into said bow] at verticallyspaced locations near the bottom of said bowl and thereabove, a valvemember movable in said body into and out of engagement with said seat;said valve member and body defining a chamber which has restrictedcommunication with the portions of said passage which are respectivelyupstream and downstream of said seat; said valve member having areas onopposite sides thereof which are exposed to fluid under pressure in saidchamber and in said upstream passage portion; said restrictedcommunication being such that when air flows into and from said chambervia said restricted communication, the air pressure in said chamber issufficient to hold the valve member in engagement with said seat toprevent air flow through said passage; the restricted communicationbetween said upstream passage portion and said chamber further beingsuch that when the water level in the bowl rises sufficiently tocommence to flow through said restricted communication into saidchamber, the pressure drop of the water therein permits the air pressurein said chamber to be decreased through the restricted communication ofsaid chamber with said downstream passage portion whereby predominantwater ressure in the upstream passage portion acts on said valve memberto move the latter out of engagement with said seat for upward flow ofwater through said downwardly extending portion thereby effectingdrainage of water through said passage until the water level in saidbowl falls to said lower opening.

2. The valve of claim I wherein the area of said valve member which isexposed to fluid pressure in said chamber is greater than the areathereof which is exposed to fluid pressure in said upstream passageportion.

3. The valve of claim 1 wherein the air pressure drop across therestricted communication between said chamber and said downstreampassage portion is respectively greater than and less than the air andwater pressure drops across the restricted communication between saidchamber and said upstream passage portion.

4. The valve of claim 1 wherein the flow capacity of the restrictedcommunication between said chamber and said downstream passage portionis less than the flow capacity of the restricted communication betweensaid chamber and said upstream passage portion thus to effect buildup ofair pressure in said chamber to retain said valve member in engagementwith said seat and to minimize leakage of air to the downstream passageportion via such restricted communication.

5. The valve of claim 1 wherein the restricted communication betweensaid upstream passage portion and said chamber comprises an annularclearance between said valve member and a bore in said body in whichsaid valve member moves into and out of engagement with said seat.

6. The valve of claim 1 wherein the restricted communication betweensaid chamber and said downstream passage portion comprises an orifice insaid valve member which opens to an annular clearance between said valvemember and a bore in said body in which said valve member moves into andout of engagement with said seat.

7. The valve of claim 1 wherein said upper opening is at least at thelevel of the restricted communication between said upstream passageportion and said chamber whereby when the water level in said bowl risestherein and within said downwardly extending portion to commence to flowthrough said last mentioned restricted communication the valve memberwill be moved out of engagement with said seat as aforesaid.

8. The valve of claim 1 wherein said downwardly extending portioncomprises a skirt member spaced around said body; said skirt memberhaving an orifice at its upper end to define said upper opening andbeing open at its lower end to define said valve member is moved out ofengagement with said se at.

9. The valve of claim 1 wherein said body extends into and is sealed inan opening through the bottom of said bowl; and

wherein said downstream passage portion extends above the lower endthereof to cause upward flow of water 5 downwardly mmuflh said y Waterdl'ainafle now from through said downwardly extending portion fordischarge through said upstream and downstream passage portions when thebottom of said bowl.

1. An automatic drain valve for an air line filter and the like having awater collecting bowl comprising a valve body having a passage throughwhich water in the bowl may be drained and having a valve seat; saidpassage, upstream of said seat, having a downwardly extending portionwhich has upper and lower openings leading into said bowl at verticallyspaced locations near the bottom of said bowl and thereabove, a valvemember movable in said body into and out of engagement with said seat;said valve member and body defining a chamber which has restrictedcommunication with the portions of said passage which are respectivelyupstream and downstream of said seat; said valve member having areas onopposite sides thereof which are exposed to fluid under pressure in saidchamber and in said upstream passage portion; said restrictedcommunication being such that when air flows into and from said chambervia said restricted communication, the air pressure in said chamber issufficient to hold the valve member in engagement with said seat toprevent air flow through said passage; the restricted communicationbetween said upstream passage portion and said chamber further beingsuch that when the water level in the bowl rises sufficiently tocommence to flow through said restricted communication into saidchamber, the pressure drop of the water therein permits the air pressurein said chamber to be decreased through the restricted communication ofsaid chamber with said downstream passage portion whereby predominantwater pressure in the upstream passage portion acts on said valve memberto move the latter out of engagement with said seat for upward flow ofwater through said downwardly extending portion thereby effectingdrainage of water through said passage until the water level in saidbowl falls to said lower opening.
 2. The valve of claim 1 wherein thearea of said valve member which is exposed to fluid pressure in saidchamber is greater than the area thereof which is exposed to fluidpressure in said upstream passage portion.
 3. The valve of claim 1wherein the air pressure drop across the restricted communicationbetween said chamber and said downstream passage portion is respectivelygreater than and less than the air and water pressure drops across therestricted communication between said chamber and said upstream passageportion.
 4. The valve of claim 1 wherein the flow capaCity of therestricted communication between said chamber and said downstreampassage portion is less than the flow capacity of the restrictedcommunication between said chamber and said upstream passage portionthus to effect buildup of air pressure in said chamber to retain saidvalve member in engagement with said seat and to minimize leakage of airto the downstream passage portion via such restricted communication. 5.The valve of claim 1 wherein the restricted communication between saidupstream passage portion and said chamber comprises an annular clearancebetween said valve member and a bore in said body in which said valvemember moves into and out of engagement with said seat.
 6. The valve ofclaim 1 wherein the restricted communication between said chamber andsaid downstream passage portion comprises an orifice in said valvemember which opens to an annular clearance between said valve member anda bore in said body in which said valve member moves into and out ofengagement with said seat.
 7. The valve of claim 1 wherein said upperopening is at least at the level of the restricted communication betweensaid upstream passage portion and said chamber whereby when the waterlevel in said bowl rises therein and within said downwardly extendingportion to commence to flow through said last mentioned restrictedcommunication the valve member will be moved out of engagement with saidseat as aforesaid.
 8. The valve of claim 1 wherein said downwardlyextending portion comprises a skirt member spaced around said body; saidskirt member having an orifice at its upper end to define said upperopening and being open at its lower end to define said lower opening,said orifice being operative to prevent air from being trapped as thewater level rises between said skirt member and said body and furtherbeing operative to permit air pressure acting on the water outside saidskirt member and above the lower end thereof to cause upward flow ofwater through said downwardly extending portion for discharge throughsaid upstream and downstream passage portions when said valve member ismoved out of engagement with said seat.
 9. The valve of claim 1 whereinsaid body extends into and is sealed in an opening through the bottom ofsaid bowl; and wherein said downstream passage portion extendsdownwardly through said body for water drainage flow from the bottom ofsaid bowl.